Ants from the Grave of Thomas Say

Among the first species that students of North American ants learn is Tapinoma sessile, the odorous house ant.

This small brown insect lives in nearly every temperate habitat across the continent. Sonoran desert washes? Check. Alpine meadows in the Sierra Nevada? Check. Wheat fields in Nebraska? Check. Long Island suburbs? Also. My kitchen? All over the place.

Tapinoma sessile was named by Thomas Say, a naturalist living in the utopian settlement of New Harmony, Indiana in the 1820s. Say is widely considered to be the father of American entomology, first discovering and describing more than a thousand of our familiar insects: the Colorado potato beetle, thief ant, cinch bug, several malaria mosquitoes, some cicadas, parasitic wasps, and so forth. Tapinoma sessile was among his final creations, published posthumously in 1836.

Scientific names of most species are stabilized by anchoring them- in a legal framework- to physical specimens kept in museums. These key name-bearing specimens are called types, and they are useful in resolving arguments concerning the validity of names, or whether a particular name ought apply to a particular population of organisms. As you might imagine, types are important. Without them taxonomists lose the connection between the names and the corresponding flesh-and-blood organisms.

Until recently, Tapinoma sessile has had no type specimen. Say’s collection was mostly lost in the years following his death in 1834. With it vanished any trace of the insects Say looked at when he penned his description of the ant. The odorous house ant has been taxonomically adrift ever since.

Where I am going with this?

Well. I am pleased to see that myrmecologist Chris Hamm has finally done the deed and provided a new type for this important ant. Chris published a paper in Annals of the Entomological Society of America primarily to describe a western species, T. schreiberi, but in the process he selected a neotype for the familiar odorous house ant.

At last, a physical specimen to bear the name T. sessile! That’s not the best part, though. Below is the text of the label affixed to the type: Chris didn’t pick just any old Tapinoma to serve as the type. He actually went to Thomas Say’s final resting place and plucked the nearest ants.

photo by Roy Snelling

That’s a fitting homage to the man who established descriptive entomology on this continent.